The primary focus of the proposed research will be to study the biological basis of implicit memory function. Specifically, patients with unilateral neocortical lesions will be assessed on a variety of implicit memory tests. Subjects will include patients with dorsolateral prefrontal lesions, patients with temporal-parietal lesions, and patients with occipital lesions. Various tests of implicit memory (e.g., tests of perceptual, lexical, and semantic priming) and various stimulus material (e.g., verbal, nonverbal) will be used to determine patterns of impairment on these tests in patients with neocortical lesions. It is predicted that secondary sensory areas (e.g., prestriate occipital areas) will be critical for perceptual priming, temporal-parietal associational areas will be critical for lexical priming, and frontal areas will be critical for semantic priming.